Abstract Alcohol?s ability to alleviate stress is theorized to represent a core underlying factor in the development of Alcohol Use Disorder (AUD). Of note, researchers conducting human alcohol administration studies are often faced with a compromise between mechanistic precision and ecological validity. Studies employing relatively precise, objective measures such as fMRI often struggle to incorporate key elements of real-world drinking contexts (e.g., social settings), while studies conducted in relatively rich ecologically valid settings may be limited in terms of outcome assessments, relying mainly on self-reports. Therefore, it is an ongoing challenge to conduct research that offers both mechanistic precision and also integrates key elements of real- world drinking contexts. The proposed study aims to move towards the identification of a paradigm that strikes this balance, using novel alcohol administration methods integrating electrophysiological measures of threat sensitivity as well as in-vivo social context. In line with the National Institute of Mental Health?s stated goal for the Research Domain Criteria (RDoC) project, the proposed study will measure the error-related negativity (ERN)?a biomarker of sustained threat/stress in RDoC?s Negative Valence Systems domain?that is found in a social context. More specifically, this study will assess how alcohol?s effects on the ERN may differ based on individual-level (e.g., anxiety, stress) and group-level (e.g., social familiarity) factors. The proposed research will be a unique contribution to my sponsor?s ongoing funded study that, once completed, will represent one of the larger alcohol administration studies conducted to date. Two hundred (half female) social drinkers aged 21?30 will be grouped into 100 dyad groups of either strangers or friends. Each group will be randomly assigned to drink either a moderate dose of alcohol or a non-alcoholic control beverage, and they will be allowed to interact freely. After the drinking period, participants? ERNs will be measured while they perform the Flanker task in the presence of the other participant (either a stranger or a friend) in the dyad. Self- reported trait anxiety will also be assessed. The proposed study is innovative in that it is, to our knowledge, the first alcohol administration study to incorporate the measurement of ERN together with a manipulation of social context in order to examine the impact of alcohol on sensitivity to threat. The funding of this project will provide substantial training to an emerging predoctoral researcher in ethics, advanced approaches to research, quantitative methods, and career development. Overall, this project will shed light on how alcohol and social context may influence individuals? threat sensitivity, with implications for prevention and intervention for problematic drinking. Specifically, the current study could have several important conceptual and clinical implications, including for understanding mechanisms underlying AUD vulnerability, identifying individuals at risk for AUD, improving reinforcement-centered harm reduction and prevention-focused interventions, and refining the understanding of high-risk relapse settings for those in treatment.